A new optical technique based on real-time color holographic interferometry has been developed for analyzing unsteady aerodynamic wakes in fluid mechanics or for measuring displacements and deformations in solid mechanics. The technique's feasibility is demonstrated here. It uses three coherent wavelengths produced simultaneously by a cw laser (mixed argon and krypton). Holograms are recorded on single-layer panchromatic silver halide (Slavich PFG 03C) plates. Results show the optical setup can be adjusted to obtain a uniform background color. The interference fringe pattern visualized is large and colored and exhibits a single central white fringe, which makes the zero order of the interferogram easy to identify. An application in a subsonic wind tunnel is presented, in which the unsteady wake past a cylinder is recorded at high rate.

The displacements of the tympanum of guinea pigs undergoing the action of acoustic impulses were investigated using holographic interferometry. The motion of the umbilicus is approximately 7.5 times smaller than that of the maximum elongation point of the tympanic membrane located between the umbilicus and the annulus fibrocartilagineus in the prolongation of the manubrium mallei. The results attempt to explain why tympanic lesions originated under the action of acoustic impulses frequently appear in the lower area of the pars tensa in the case of guinea pigs, The holographic visualization of tympanic-membrane displacements appears to offer a number of practical applications allowing to throw light into the transmission of acoustic energy at the level of the tympanic membrane. Subject Classification: 65.24; 35.65; 80.50.

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Quantitative results concerning TV-holography and shearography associated with endoscopy are presented here. In both cases, a c.w. argon laser has been used. Moreover, shearography experiments have been performed with the help of a pulsed YAG laser working at 25 Hz.